For example, a manufacturing apparatus for semiconductor devices transfers an object to be processed, such as semiconductor wafer and LCD substrate (the object will be referred “wafer etc.”, after) from a loading/unloading part to a processing part, e.g. a cleaning/drying part by using a transport mechanism. At the cleaning/drying part, a wafer etc. held by a rotor equipped with a rotating mechanism is cleaned in order to remove contaminations, such as particles, organic contaminants and metallic impurities, and post-etching polymers from the wafer etc. with supply of designated chemical liquid, deionized water or the like. After the removal, the wafer etc. is dried by removing droplets therefrom with supply of inert gas, for example, nitrogen (N2) gas, volatile and hydrophilic IPA vapor, etc. Subsequently, an operation to pick up the wafer etc. from the cleaning/drying part and further transfer the wafer etc. to the loading/unloading part by the transport mechanisms is performed.
In the semiconductor manufacturing apparatus like this, of course, a motor (rotation driving apparatus) driven by a supply voltage from a power source is used in a rotor, as a driving source for the transport mechanism.
By the way, during the operation of the apparatus, there arises a situation that the supply voltage for the motor drops. In such a situation, the processing is immediately suspended for purpose of protecting the rotor and the transport mechanism. However, the standstill of the processing may cause the quality of a wafers etc. to deteriorate.
Therefore, there has been hitherto adopted a method that if the supply voltage drops due to power blackout etc., then a processing condition is memorized by a power source supplied from power reserving means and further, when the voltage drop is recovered, the processing operation is restarted while referring to data of the memorized processing condition. This method is disclosed in e.g. Japanese Patent Publication No. 2723764, paragraph Nos. 0011, 0024 to 0028 and 0031 and FIGS. 4 and 5. Additionally, there is also known a method that when a power blackout occurs, the transportation of wafers etc. or the processing operation is maintained by an emergency power from an emergency power source. This method is disclosed in e.g. Japanese Patent Publication (Kokai) No. 10-150014, paragraph Nos. 0033, 0040 and 0041 and FIG. 5.
In the above-mentioned method that the processing condition is memorized by the power source supplied from the power reserving means when the supply voltage drops and that the processing operation is maintained while referring to data of the memorized processing condition when the voltage drop is recovered, however, there are problems to be solved. That is, since the operation (driving) of the apparatus is once stopped when the supply voltage drops and the operation (driving) is restarted when the voltage drop is recovered, the driving period of the apparatus is increased to cause reduction of its throughput. Additionally, if stopping the rotation of a driving part of the apparatus during, especially, its accelerating rotation or high-speed rotation, the wafers etc. may be damaged due to vibration of the apparatus. Similarly, the other method of continuing the processing operation with supply of the emergency power from the emergency power source at a power blackout has problems although there is no problem of increasing the processing period remarkably. That is, since the driving of the apparatus comes to a temporary standstill in changing a main power supply to the emergency power source, the driving period is increased as much to cause reduction of the throughput. Additionally, as mentioned above, if stopping the rotation of a driving part of the apparatus during, especially, its accelerating rotation or high-speed rotation, the wafers etc. may be damaged due to vibration of the apparatus.
By the way, such a situation that a supply voltage drops is not always derived from a power blackout only. The situation may be derived from an instantaneous blackout where the voltage drops instantaneously and the power is recovered (redelivered) subsequently. Note that, the apparatus is usually standardized so as to cope with such an instantaneous blackout.
Also in case of such an instantaneous blackout, the standstill of the apparatus driving causes increasing of the driving period and reduction of the throughput. Further, there is a problem that a standstill in rotational drive causes the wafers etc. to be damaged due to vibration.
Under the above circumstance, the object of the present invention is to suppress increasing of the driving period by controlling the rotation of an apparatus corresponding to a voltage drop during driving of the apparatus, to improve the throughput of the apparatus and to suppress vibration of the apparatus due to its standstill in rotation in the voltage drop.